In a conventional smart card which is in widespread use, for example, in the electronic payment transactions sector, the communication between the chip located on the smart card and a read device is contact-based, i.e. via smart card contacts exposed towards the outside of the smart card.
For this purpose, however, for use the smart card always needs to be inserted into a corresponding read device, which a user may find objectionable. A development which solves this problem provides so-called dual-interface smart cards, in which the chip, in addition to the conventional contact-based interface, can also communicate by means of a contactless interface. The contactless interface on the smart card can have a smart card antenna, which is contained in the smart card and is connected to the chip. The smart card antenna and the chip can be arranged together on a smart card module, in which case such a miniaturized form of the smart card antenna can then be referred to as a smart card module antenna. The joint arrangement of the coil and the chip on a smart card module is also referred to as CoM (coil on module). Irrespective of the type of smart card antenna, a galvanic connection is formed between said smart card antenna and the smart card module or the chip.
In an electronic payment system, for example, a functional distance of up to 4 cm between the chip and the read unit is required. However, meeting this setpoint input can prove to be problematic since, under certain circumstances, it is not possible for a sufficiently large smart card module antenna for enabling wireless communication at the required distance to be arranged on the small area which is available on the smart card module. In order to improve the performance of the contactless communication, in addition a so-called amplifier antenna (also referred to as booster antenna) can be built into a smart card and inductively coupled to the smart card module or the smart card module antenna arranged on the smart card module. Likewise, such a booster antenna can be inductively coupled to the CoM of a purely contactless smart card for improving the performance of the contactless communication. The booster antenna can be provided on a separate layer and contained in the smart card. The separate layer which contains the booster antenna can be or can have been laminated into the smart card during manufacture of the smart card, for example. The possible read or write distance between a write or read device and the smart card module is substantially increased by the booster antenna.
FIG. 1 shows a contactless smart card 100 with a smart card body 102, a booster antenna 104 integrated (for example laminated) therein and a contactless smart card module arrangement (for example also referred to as coil on module, CoM) 106, wherein the booster antenna 104 partially surrounds the contactless smart card module arrangement 106.
The booster antenna 104 is formed by a large ring-shaped conductor loop 108, wherein a small part of the conductor loop is formed to give a small conductor loop 110 which partially surrounds the contactless smart card module arrangement 106, for example a coil on module 106, which is arranged within a peripheral region of the large conductor loop 108.
Furthermore, there are several approaches and embodiments for so-called comprehensive UHF-HF antennas. The dimensions and outline dimensions of said antennas generally correspond to conventional RFID (radiofrequency identification) labels, such as in accordance with a smart card, for example, and are generally realized by means of a combination of a dipole and HF coil.